GHSA-2XF4-CG6J-VHGQ symfony/polyfill-intl-idn: xn-- labels with ASCII-only Punycode payloads are treated as equivalent to their decoded form

Description symfony/polyfill-intl-idn provides a userland implementation of idntoutf8 and idntoascii for runtimes that lack the intl extension. Its Idn::process method decodes labels prefixed with xn-- using Punycode but never enforces the validity criterion added in UTS 46 revision 33 Section 4...